Some people perceive things wrong. Someone can be nice to someone, and that person will think they are being flirted with. Some people, it's just their personalities, and they don't even realize they're doing it. Some people are completely different people when they are online. You can say things that you normally wouldn't say because you're not face to face. I would say that it also depends on the intent. You can flirt with someone knowing fully well that you have no plans of meeting them in person.
It's never too late to become the person you were meant to be.